Efectividad de desinfectantes de superficies de los equipos en instalaciones de envasado de productos listos para su consumo

[SPA] Una de las principales fuentes de contaminación de los alimentos envasados listos para su consumo son las superficies de los equipos en contacto con los alimentos. En dichas superficies se desarrollan biofilms que con frecuencia son muy resistentes a los agentes desinfectantes utilizados en las plantas de fabricación. En este trabajo se han aislado diferentes microorganismos de biofilms en superficies de equipos, y se han estudiado frente a desinfectantes comerciales utilizados en diversas industrias alimentarias, en un equipo multiskan ascent y placas microtiter. Se estudiaron tres cepas bacterianas que pueden ser encontradas en las superficies de los equipos: Pseudomonas sp., Escherichia coli y Listeria monocytogenes. Los desinfectantes ensayados han sido quacide p40, dectocide yo2, dexacide b10, divosan activ, quacide mc7, limoseat, asep 150 y destocide. Respecto a las determinaciones de concentración minina inhibitoria (cmi) los desinfectantes mas efectivos resultaron ser quacide mc7, que a una concentración de 0.125 % v/v inhibió el crecimiento de todas las cepas diana y asep 150 que produjo el mismo efecto a una concentración de 0,06%. La definición de concentración mínima bactericida (cmb) se estableció como el valor de concentración del desinfectante que destruye una población de 104 cel./ml durante 20 min. Las cmb más bajas se obtuvieron con dexacide b10 con cmb = 0,125% para todas las cepas estudiadas y quacide mc7 con cmb = 0,0625% para l. Monocytogenes y e. Coli y de cmb =0,125% para Pseudomonas sp. Como conclusión se recomienda utilizar una alternancia de desinfectantes dependiendo del tipo de cepa predominante que contamine la superficie de los equipos. [ENG] The main contamination sources of packaged ready to eat products are equipment surfaces which keep in touch with them during the production process. Microbial biofilms are developed on these surfaces and frequently they are resistant to common disinfectants used in the food industry. Different spoilage microorganisms which usually are found on equipment surfaces biofilms have been tested in the present work. Their resistance against comercial disinfectants was studied in a Multiskan Ascent spectrophotometer and microtitter plates (96 wells). Three strains isolated from the equipment surfaces were tested: Pseudomonas sp., Escherichia coli y Listeria monocytogenes. Disinfectants were Quacide P40, Dectocide YO2, Dexacide B10, Divisan activ, Quacide MC7, Limoseat, Asep 150 y Destocide. The minimal inhibitory concentration (MIC) and the minimal bactericidal concentration (MBC) were determined for each strain. The most effective disinfectants regarding the MIC values were Quacide MC7 and Asep 150 which inhibited the growing of the target strains at concentrations of 0,125 and 0,06 % v/v respectively. The MBC was defined as the minimal concentration at which the strain population of 104 cell/ml was killed during 20 minutes of interaction between the strain and each disinfectant. The lowest values of MBC were 0,125 % v/v with Dexacide B10 for all the target strains and 0,0625 % v/v with Quacide MC7 for L. monocytogenes and E.coli and 0,125 % v/v for Pseudomonas sp. As conclusion we recommend the use of a disinfection plan in relation to the predominant spoiling microflora and the potential risk that represents for the food product. This plan would include several disinfectants changing them each few days

Influencia de la limpieza del aire y de las superficies en instalaciones de envasado sobre la vida útil de productos agroalimentarios

[SPA] Algunos de los factores que más influyen sobre la calidad y la vida útil de los alimentos envasados no asépticamente son la carga microbiana inicial del producto antes de su procesado y la carga aportada durante el desarrollo de este procesado y del envasado, que tendrá como resultado la carga microbiana final del producto envasado. Esta carga microbiana dependerá en gran medida de la contaminación del aire de la sala de envasado y de las superficies de los equipos en contacto con el producto. Es por ello, que se ha llevado a cabo este estudio de caracterización y correlación de toda una serie de parámetros relativos al aire de la sala de envasado: temperatura, humedad relativa, velocidad del aire, concentración de partículas, recuento de unidades formadoras de colonias (UFC) en el aire, y la carga microbiana de las superficies de los equipos en contacto con el producto que se envasa. Esta carga microbiana del aire y de las superficies se ha relacionado con la evolución y vida útil de muestras de carne de cerdo y pavo cocido, que se han loncheado y envasado bajo dos condiciones de limpieza del aire y superficies: (i) en aire filtrado con flujo laminar (FL) (equivalente a sala blanca clase 100), y (ii) en condiciones de salas convencionales (SC) (en sala clase 100.000), y, posteriormente, se han almacenado a 4ºC. Las muestras se analizaron periódicamente hasta el final de su vida útil, determinando: la carga de enterobacterias, microflora total mesófila, microflora psicrotrofa, microflora láctica, Staphylococcus spp. Y Listeria monocytogenes; también, se determinaron los cambios organolépticos y de pH. Con la tecnología de loncheado y envasado en condiciones de flujo laminar se consiguió una mayor proporción de producto con recuentos inferiores a 10 UFC/g. En todos los casos, las muestras de carne de cerdo cocido presentaron valores inferiores a 104 UFC/g, y las de pavo cocido inferiores a 103 UFC/g. Esta significativa disminución de la carga microbiana inicial de los productos recién loncheados y envasados se tradujo en un claro aumento de su vida útil, en refrigeración a 4º C, que se amplió desde 18,6 días a 35,0 días, en el caso de la carne de cerdo cocida, y desde 32,3 a 49,2 días en el caso de la carne de pavo cocida. [ENG] The most important factors influencing the shelf life of cooked, sliced and packed meat products are the initial product quality and the factors of cutting and packaging process, mainly that’s concerning to the contamination control of air and equipment surfaces in contact with the product. This contamination will influences on the microbial load of the packaged product. Therefore the interest of the accomplishment of these operations protecting the The most important factors influencing the shelf life of cooked, sliced and packed meat products are the initial product quality and the factors of cutting and packaging process, mainly that’s concerning to the contamination control of air and equipment surfaces in contact with the product. This contamination will influences on the microbial load of the packaged product. Therefore the interest of the accomplishment of these operations protecting the product from the microbial contamination, using a cover of laminar flow with filtered air on the packaging line. In this study the shelf life of cooked ham and cooked turkey meat, sliced, packaged and stored in refrigeration (at 4º C) is analyzed, as function on the initial microbial load of the product, and the packaging technology: (i) under laminar flow (class 100 clean room) and (ii) in conventional clean room (class 100,000). The sliced and packaged product samples have been analyzed periodically until the end of their shelf life, determining the load of enterobacteriaceae, total mesophilic microflora, psychrotrophic microflora, lactic acid microflora, Staphylococcus spp. and L. monocytogenes in the samples. Also, they have been determined the changes in organoleptic properties, and pH. With the packaging technology using laminar flow a greater proportion of product just packaged with counts less than 10 UFC/g is obtained, and, in all the cases, sliced meat samples with counts less than of 104 UFC/g were observed in cooked ham, and less than 103 CFU/g were observed in cooked turkey meat. This significant diminution of microbial load in the product just packaged results in a clear increase of its shelf life at 4ºC, extending it from 18,6 days to 35 days in the case of sliced cooked ham, and from 32,3 to 49,2 days in the case of sliced cooked turkey meat

Search for Higgs boson decays into a pair of light bosons in the bbμμ final state in pp collision at √s=13 TeV with the ATLAS detector

A search for decays of the Higgs boson into a pair of new spin-zero particles, H→aa, where the a-bosons decay into a b-quark pair and a muon pair, is presented. The search uses 36.1fb−1of proton–proton collision data at √s=13 TeV recorded by the ATLAS experiment at the LHC in 2015 and 2016. No significant deviation from the Standard Model prediction is observed. Upper limits at 95% confidence level are placed on the branching ratio (σH/σSM) ×B(H→aa →bbμμ), ranging from 1.2 ×10−4to 8.4 ×10−4in the a-boson mass range of 20–60GeV. Model-independent limits are set on the visible production cross-section times the branching ratio to the bbμμ final state for new physics, σvis(X) ×B(X→bbμμ), ranging from 0.1fb to 0.73fb for mμμ between 18 and 62GeV

Efecto antimicrobiano de vainillina y de aceites esenciales de canela y clavo en leche de vaca pasteurizada

OBJETIVOS: El propósito de este estudio fue determinar la actividad antimicrobiana de los aceites esenciales (AEs) de corteza de canela, hojas de canela y de clavo y de los compuestos puros eugenol, cinamaldehído y vainillina frente a Listeria monocytogenes Scott A y Escherichia coli O157:H7 y el efecto de la vainillina sobre la termorresistencia de L. monocytogenes Scott A en leche de vaca semidescremada. METODOLOGIA: Se determinó la Concentración Mínima Inhibitoria (CMI) y la Concentración No Inhibitoria (CNI) de los antimicrobianos en Caldo Tripticasa de Soja (CTS) mediante el modelado de la curva dosis-respuesta obtenida al graficar las áreas fraccionadas frente a la concentración de antimicrobiano, a pH 6 y 7. También se determinaron las Concentraciones Parcialmente Inhibitorias (CPIs) y las Concentraciones Mínimas Bactericidas (CMBs). La actividad de las combinaciones de antimicrobianos se determinó mediante el método del tablero de ajedrez, que permitió obtener la Concentración Fraccionada Inhibitoria de las mezclas (CFI) y los isobologramas correspondientes. La actividad de los antimicrobianos y sus combinaciones se determinó también en leche pasteurizada de vaca con diferentes concentraciones de grasa (entera, semidesnatada y desnatada) a temperaturas de 7 ºC y 35 ºC. La resistencia térmica de L. monocytogenes Scott A se ensayó en leche semidescremada calentada a 55 ºC, 58 ºC, 60 ºC y 62 ºC con 900, 1400 y 1800 ppm de vainillina. Dos modelos matemáticos se usaron para ajustar los datos obtenidos: el modelo “shoulder+log-linear” de Geeraerd y el modelo Weibull. RESULTADOS Y DISCUSION: E. coli 157:H7 fue más resistente a los AEs de corteza de canela, hojas de canela y clavo que L. monocytogenes. La vainillina y el cinamaldehido mostraron una actividad antimicrobiana similar frente a los dos microorganismos. El antimicrobiano con menor CMI frente a L. monocytogenes fue el AE de corteza de canela seguido por el AE de clavo, cinamaldehído el AE de hojas de canela, el eugenol y la vainillina. La menor CMI frente a E. coli O 157:H7 la presentó el cinamaldehido, seguido por el AE de corteza de canela, el eugenol, el AE de clavo, el AE de hojas de canela y la vainillina. Los antimicrobianos con menor CMB, fueron el eugenol, los AEs de clavo y hojas de canela seguidos por el cinamaldehido, el AE de corteza de canela y la vainillina. El pH no afectó los valores de CMI ni de CMB. Todas las combinaciones de antimicrobianos ensayadas fueron aditivas para L. monocytogenes; para E. coli O157:H7 las mezclas con AE de corteza de canela fueron indiferentes y las mezclas con vainilla fueron sinérgicas. En la leche de vaca el AE de corteza de canela fue el antimicrobiano más efectivo, seguido por el AE de clavo, AE de hojas de canela y la vainillina. Los AEs de canela y clavo aumentaron su actividad antimicrobiana en las mezclas, especialmente las combinaciones de AEs con vainilla. La incubación a bajas temperaturas y el menor contenido de grasa de la leche aumentó la actividad antimicrobiana de los AEs. La incorporación de vainillina en la leche disminuyó la termorresistencia de L. monocytogenes, incrementando la tasa de muerte y disminuyendo la longitud del hombro de las curvas de destrucción térmica, efecto que fue más evidente cuando se usaron las temperaturas más bajas. CONCLUSIONES: La vainillina y los AEs de corteza de canela, hojas de canela y clavo presentan actividad antimicrobiana en leche de vaca frente a L. monocytogenes y E. coli O 157:H7. Las dosis necesarias de los antimicrobianos para producir la inhibición se reducen combinando los antimicrobianos entre sí. El uso de concentraciones sub-inhibitorias de vainillina en leche semidescremada favorece la inactivación térmica de L. monocytogenes. OBJETIVES: The purpose of this study was to determine the antimicrobial activity of cinnamon bark, cinnamon leaves and clove essential oils (EOs) against Listeria monocytogenes Scott A and Escherichia coli O157:H7 and the effect of vainillin on the thermal resistance of L. monocytogenes Scott A in semiskim cow’s milk. METHODOLOGY: The MIC (Minimal Inhibitory Concentration) and the NIC (Non Inhibitory Concentration) of the antimicrobials was determined in Trypticase Soy Broth (TBS), modelling the dose-response curve based on the fractional area against the concentration of antimicrobial. Partially Inhibitory Concentrations (PICs) and Minimum Bactericidal Concentrations (MBCs) were also determined. The FICs (Fractional Inhibitory Concentrations) index of mixtures of antimicrobials was established by the checkerboard method and the corresponding isobolograms. The activity of the antimicrobials and their combinations was determined in pasteurised cow’s milk. The effect of storage temperatures (7 °C and 35 °C) and the effect of milk fat on the antimicrobial activity was also evaluated. Finally, the heat resistance of L. monocytogenes in pasteurized cow’s milk heated to moderate temperatures (55, 58, 60 and 62°C) with different levels of vanillin (900, 1400 and 1800 ppm) was studied. Two models were used to fit the data: the “shoulder+loglinear” model and the Weibull model. RESULTS AND DISCUSSION. The antimicrobial with the lowest MIC against L. monocytogenes was cinnamon bark EO, followed by clove EO, cinanaldehyde, cinnamon leaves EO, eugenol and vanillin. The antimicrobial with the lowest MIC against E. coli O 157H was cinamaldehyde followed by cinnamon bark EO, eugenol, clove EO, cinnamon leaves EOs and vanillin. The pH did not affect the MICs and CNIs values. The antimicrobial with the lowest MBC against L. monocytogenes was clove EO, followed by eugenol, cinnamon leaves EO, cinnamon bark EO, cinamaldehyde, and vanillin. The antimicrobial with the lowest MBC against E. coli O157:H7 was eugenol followed by clove EO, cinnamon leaves EO, cinamaldehyde, cinnamon bark EO and vanillin. Mixtures of all EOs were additive against L. monocytogenes; against E. coli O157:H7mixtures with cinnamon bark EO were indifferent and mixtures with vanillin were synergistic. The antimicrobial with the highest antimicrobial activity in semi-skim cow’s milk was cinnamon bark EO, followed by clove EO, cinnamon leaves EO and vanillin. Incubations in milk with low fat content or at low temperature increased the antimicrobial activity. Mixtures of EOs increased the antimicrobial activity of individual components and combinations with vanillin were the most effective. Thermal resistance of L. monocytogenes in milk was reduced by vanillin at all temperatures tested. Vanillin increased the death rate and reduced the shoulder length of L. monocytogenes of thermal destruction curves in milk. This effect was more evident when working at lower temperatures. CONCLUSIONS: Cinnamon bark, cinnamon leaves and clove EOs show antimicrobial activity in pasteurized cow’s milk. Antimicrobial mixtures reduce the concentration of individual components to inhibit microbial growth. Sub-inhibitory concentrations of vanillin in semiskim milk increase the thermal inactivation of L. monocytogenes

Synergistic Antimicrobial Activities of Combinations of Vanillin and Essential Oils of Cinnamon Bark, Cinnamon Leaves, and Cloves

Plant bioactive compounds have antimicrobial and antioxidant activities that allow them to be used as a substitute for synthetic chemical additives in both food and food packaging. To improve its sensory and bactericidal effects, its use in the form of effective combinations has emerged as an interesting possibility in the food industry. In this study, the antimicrobial activities of essential oils (EOs) of cinnamon bark, cinnamon leaves, and clove and the pure compounds vanillin, eugenol, and cinnamaldehyde were investigated individually and in combination against Listeria monocytogenes and Escherichia coli O157:H7. The possible interactions of combinations of pure compounds and EOs were performed by the two-dimensional checkerboard assay and isobologram methods. Vanillin exhibited the lowest antimicrobial activity (MIC of 3002 ppm against L. monocytogenes and 2795 ppm against E. coli O157:H7), while clove and cinnamon bark EOs exhibited the highest antimicrobial activity (402–404 against L. monocytogenes and 778–721 against E. coli O157:H7). For L. monocytogenes, pure compound eugenol, the main component of cinnamon leaves and clove, showed lower antimicrobial activity than EOs, which was attributed to the influence of the minor components of the EOs. The same was observed with cinnamaldehyde, the main component of cinnamon bark EO. The combinations of vanillin/clove EO and vanillin/cinnamon bark EO showed the most synergistic antimicrobial effect. The combination of the EOs of cinnamon bark/clove and cinnamon bark/cinnamon leaves showed additive effect against L. monocytogenes but indifferent effect against E. coli O157:H7. For L. monocytogenes, the best inhibitory effects were achieved by cinnamon bark EO (85 ppm)/vanillin (910 ppm) and clove EO (121 ppm)/vanillin (691 ppm) combinations. For E. coli, the inhibitory effects of clove EO (104 ppm)/vanillin (1006 ppm) and cinnamon leaves EO (118 ppm)/vanillin (979 ppm) combinations were noteworthy. Some of the tested combinations increased the antimicrobial effect and would allow the effective doses to be reduced, thereby offering possible new applications for food and active food packaging